I'd say they both seem extremely weak. The 2p would in theory save you 100 Rage a minute, but what else are you going to spend it on? Mauling for maybe an extra 120k damage total? Healing yourself when you're probably topped up anyway, seeing how you just had a massive damage reduction? And the 4p - just what we needed, another Leader of the Pack..

Besides just weaving in Barkskin to extend SD uptime, I'd likely use it in a similar manner when we had the tier bonus of upon Barkskin expiring we received extra dodge chance: preemptive mechanics cooldown.

In raids where we tend to have many abilities that may threaten our survivability that occur at regular intervals, clever use of Barkskin with this 2pc can do what we might already do in one button push. For example, if you time your Barkskin us on a typical "tank killer" mechanic or even some periodic burst damage, you'll have Barkskin reduce the damage of the attack, and you'll have SD running with a 40-rage FR to heal up some/all of the damage you just took... all w/o spending rage. Perhaps these are just openings I tend to look for while tanking, but I highly doubt I'm the only one. This is also highly valuable if we have to tank for extended periods of time w/o letting our SD charges build up again.

The 4pc, even on paper, seems really good. Yes, yes, it's another heal, and a HoT to boot... but it does have quite a bit of potential. First of all, it will literally be up all the time (and maybe Arielle can comment on how/if the heal refreshes/extends, since I can't do the PTR for about two weeks), and that's not something to complain about. Also, the 4pc doesn't appear to rely upon how much rage you actually spend on FR to receive the heal, and if we get into situations where we run out of SD charges and are spamming FR for life (seems to happen more on heroic content than normal, but it depends on your strategy), this heal will likely matter the most. Rather curious if it's really a "heal" or a "restore/leech" effect, since we've run into a few encounters in ToT where our self-healing is debuffed. Also curious if the 4pc will proc off the 2pc!

While I could keep going on and on about potential uses of the tier bonuses, but I'll leave it at this.

It seems to me that with current mitigation mechanics 4pc may either be useless or overpowered, depending on tuning. But I wouldn't call it weak before we get experience on t16 boss fights and know what Blizzard has in store for guardians.

I still believe its weak and doesnt really fit our playstyle and the way our mechanics work. The 2p seems nice but would be cool if the Fr was a 60rage FR to use the glyph.
I can see the 4piece be not that bad with the FR glyph. both are not that bad and useable but compared to other tanks it feels very weak.

Maybe arielle will give some numbers and depends on boss fights but i am really sad about both beeing a heal cause i think we dont need more heals.

I have just been messing around with these set bonuses on ptr (mainly the 4pc, as I think the 2 pc is relatively self explanatory).

The 2 pc you don't have to plan too much around, as it will simply add the duration of the sd to the existing sd you have on yourself should you have one. It is like exo mentioned very reminiscent of the bonus in firelands (t12), and will probably get used similarly, knowing that you have this extra thing when barkskin expires means you have to think a little bit ahead, but on the other hand I really don't think that would be required for most normal every day play.

The 4pc, it does stack, with ~ 660k hp I managed to get it to about 20k tick every second in a burst situation, i.e. lots of rage + all 3 charges of SD ready, and spamming a few FR in between, (you can make a very simple weak aura for it as the tooltip says "Healing for x every 1 sec") with MoU with the glyph I got it up to ~30k ticks on a burst. But realistically for most situations the hot is going to tick every second for between 9k and 13-14k depending on your gear. I tried the spamming of fr 24/7 to see what I could get out of it, but it came to a very similar number ~ 12k or so, but ofc you don't ever use sd.

So if you were to think of it as a hot for 12-13k hps, its not too bad, I obviously haven't tried it in a raid or any useful situation to see how it pans out in reality with everything else. I quite like both the set bonuses, but I think I will hold out on judgement until I see it in action in a raid, and can have a better idea of how well its tuned.